ndarray-normalize with sample statistics

[bldrvnlw]

Since I needed a different version of normalization I've copied, modified and renamed ndarray-normalize to ndarray-sample-normalize. This performs the normalization with the sample statistics, i.e. the n-1 calculation for the standard deviation.

See Wikipedia Standard Deviation. See also the matlab zscore function which has a flag 0 - for sample standard deviation and 1 - for population standard deviation.

The repository is at https://github.com/bldrvnlw/ndarray-sample-normalize including an operational test. Would people be intrested in having this in scijs?

An alternative might be to add a flag to the original ndarray-normalize instead.